The present invention relates to a process for the preparation of ruthenium(III) chloride (RuCl3), as well as to a process for the purification of ruthenium(III) chloride (RuCl3) and a use of the process for the preparation or the purification of ruthenium(III) chloride (RuCl3).
The preparation of ruthenium(III) chloride is well known in the art. For example, it is known to prepare ruthenium(III) chloride by the thermal decomposition of ammonium hexachlororuthenate(IV), the subsequent treatment of the obtained metal with a mixture of NaOH and NaOCl, and reducing the obtained Na2RuO4 to RuO2, which is then filtered and washed. In the following, the obtained RuO2 is treated with hydrochloric acid for obtaining a raw solution of ruthenium(III) chloride. However, the raw ruthenium(III) chloride solution is typically purified by distillation, for which the ruthenium(III) chloride must be first oxidized to ruthenium(IV) oxide, which is then distilled. Finally, the distilled ruthenium(IV) oxide is reduced again to ruthenium(III) chloride.
A disadvantage of the above-mentioned process is that the purification of the raw solution of ruthenium(III) chloride by distillation has to be carried out in a cascade of numerous steps, including an oxidizing step, the distillation of the oxidized product, and the subsequent reduction of the oxidized product back to the final ruthenium(III) chloride. This kind of purification thus requires suitable and complicated distillation equipment, as well as a high amount of chemicals for the corresponding oxidizing and reducing reaction and, further, the numerous steps are time-consuming and lead to a relative high loss of ruthenium(III) chloride.
Thus, there is a need in the art for providing a process which avoids the foregoing disadvantages and especially allows for the preparation and/or purification of ruthenium(III) chloride with a high yield. In particular, it is desirable to provide a time-efficient process for the preparation and/or purification of ruthenium(III) chloride which can be carried out without complicated distillation equipment and without using a cascade of oxidizing and reducing reactions.